Estimating Probabilistic Safe WCET Ranges of Real-Time Systems at Design Stages

• Published in: ACM transactions on software engineering and methodology 2023-03, Vol.32 (2), p.1-33, Article 37
• Main Authors: Lee, Jaekwon, Shin, Seung Yeob, Nejati, Shiva, Briand, Lionel, Parache, Yago Isasi
• Format: Article
• Language: English
• Subjects: Computer systems organization; Computing methodologies; Empirical software validation; Machine learning; Real-time schedulability; Real-time systems; Search-based software engineering; Software and its engineering
• ISSN: 1049-331X; 1557-7392
• DOI: 10.1145/3546941

Estimating worst-case execution time (WCET) is an important activity at early design stages of real-time systems. Based on WCET estimates, engineers make design and implementation decisions to ensure that task executions always complete before their specified deadlines. However, in practice, engineers often cannot provide precise point WCET estimates and prefer to provide plausible WCET ranges. Given a set of real-time tasks with such ranges, we provide an automated technique to determine for what WCET values the system is likely to meet its deadlines and, hence, operate safely with a probabilistic guarantee. Our approach combines a search algorithm for generating worst-case scheduling scenarios with polynomial logistic regression for inferring probabilistic safe WCET ranges. We evaluated our approach by applying it to three industrial systems from different domains and several synthetic systems. Our approach efficiently and accurately estimates probabilistic safe WCET ranges within which deadlines are likely to be satisfied with a high degree of confidence.